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1.
This study investigated the dehydrochlorination of flexible polyvinyl chloride (PVC) containing 59.2% PVC, 29.7% dioctyl phthalate
(DOP), and approximately 12% stabilizers. Flexible PVC was treated with NaOH/ethylene glycol (NaOH/EG) solutions at NaOH concentrations
in the range 0.5–4 mol/l and was heated in a microwave heater at a temperature between 100° and 160°C for 0–30 min. All chlorides
were completely eliminated by internal heating at 160°C using microwaves for 10 min in a 1 mol/l NaOH/EG solution, and the
residue was made up of hydrocarbons. The weight loss rate reached a maximum of 74.7% at a temperature of 160°C. It was discovered
that the use of microwaves significantly shortened the reaction time compared to using conventional electric heaters or other
external heating systems and also allowed the use of lower concentrations of NaOH.
Chemical Feedstock Recycling & Other Innovative Recycling Techniques 6 相似文献
2.
3.
This study investigated the deplasticization and dechlorination of flexible polyvinyl chloride (PVC) containing 59.2% PVC, 29.7% dioctyl phthalate (DOP), and approximately 12% stabilizers. Flexible PVC was treated with NaOH solutions at concentrations in the range 2–16 mol/l and heated by microwaves to temperatures between 100° and 250°C for 0–120 min. DOP was extracted from flexible PVC into the NaOH solution as a phthalic acid salt; the remaining PVC was subsequently dechlorinated by increasing the temperature. On internal heating using microwaves, the plasticizer was 100% extracted during processing at 150°C for 30 min, whereas the chlorides were 100% removed during processing at 235°C for 30 min; the residue was converted into hydrocarbon compounds. The maximum weight loss ratio was 71% compared to the pretreatment state. It was also found that 100% deplasticization and dechlorination was possible using 8 mol/l NaOH solution, which is almost half the concentration employed when using conventional external heating systems. 相似文献
4.
Determination of nitrous oxide, methane, and ammonia emissions from a swine waste composting process 总被引:7,自引:0,他引:7
Takashi Osada Kazutaka Kuroda Michihiro Yonaga 《Journal of Material Cycles and Waste Management》2000,2(1):51-56
The amounts of harmful gas emissions from the process of composting swine waste were determined using an experimental composting
apparatus. Forced aeration (19.2–96.1 l/m3/min) was carried out continuously, and exhaust gases were collected and analyzed periodically. With weekly turning and the
addition of a bulking agent in order to decrease the moisture content and increase air permeability, the temperature of most
of the contents rose to 70°C and composting was complete within 3–5 weeks. NH3, CH4, and N2O emissions were high in the early stage of composting. About 10%–25% of the nitrogen in the raw material was lost as NH3 gas during composting. The emission rate of NH3 mainly depended on the aeration rate, so that as the aeration rate rose, the level of NH3 emissions increased. The CH4 and N2O emissions could be kept lower with adequate treatment at more than 40 l/m3/min aeration. N2O may be mainly the result of the denitrification of NO
x
-N in the additional matured compost used as a composting accelerator.
Received: September 11, 1998 / Accepted: November 8, 1999 相似文献
5.
Shohichi Osada Dalibor Kuchar Hitoki Matsuda 《Journal of Material Cycles and Waste Management》2010,12(1):83-92
To study the volatilization and condensation behaviors of low-boiling-point elements in the waste melting process, experiments
were conducted to collect the dust from a coke-type incineration residue melting furnace. Then, a comparison was made between
the experimental results and the calculated values obtained from a thermodynamic equilibrium model in terms of the chemical
composition of the dust. The composition of the dust collected from a cylindrical filter in the exhaust gas duct was determined
by chemical methods, scanning electron microscopy/energy-dispersive X-ray spectroscopy, and X-ray analysis. As a result, the
sampled dust was classified into two different types: fine particles mainly containing Na, K, Pb, and Zn collected from the
side face of the cylindrical filter, and large particles containing Ca, Si, and Al collected from the bottom face of the cylindrical
filter. From X-ray analysis of the sampled dust, NaCl, KCl, PbS, and ZnS were identified in the fine-particle dust, while
CaO, SiO2, Al2O3 were detected in the large-particle dust. From the results of the thermodynamic equilibrium calculation in the gas cooling
process from 2000 to 600 K, it was found that Na, K, Pb, and Zn volatilized as metals in the melting furnace were condensed
as alkali chlorides such as NaCl and KCl and heavy metal sulfides such as PbS and ZnS. These computational results were in
good agreement with the X-ray diffraction results of the sampled dust at a gas temperature of 823 K for the formation of NaCl,
KCl, PbS, and ZnS. 相似文献
6.
This study evaluates the effects of co-gasification of municipal solid waste with and without the municipal solid waste bottom ash using two large-scale commercial operation plants. From the viewpoint of operation data, there is no significant difference between municipal solid waste treatment with and without the bottom ash. The carbon conversion ratios are as high as 91.7% and 95.3%, respectively and this leads to significantly low PCDD/DFs yields via complete syngas combustion. The gross power generation efficiencies are 18.9% with the bottom ash and 23.0% without municipal solid waste bottom ash, respectively. The effects of the equivalence ratio are also evaluated. With the equivalence ratio increasing, carbon monoxide concentration is decreased, and carbon dioxide and the syngas temperature (top gas temperature) are increased. The carbon conversion ratio is also increased. These tendencies are seen in both modes.Co-gasification using the gasification and melting system (Direct Melting System) has a possibility to recover materials effectively. More than 90% of chlorine is distributed in fly ash. Low-boiling-point heavy metals, such as lead and zinc, are distributed in fly ash at rates of 95.2% and 92.0%, respectively. Most of high-boiling-point heavy metals, such as iron and copper, are distributed in metal. It is also clarified that slag is stable and contains few harmful heavy metals such as lead. Compared with the conventional waste management framework, 85% of the final landfill amount reduction is achieved by co-gasification of municipal solid waste with bottom ash and incombustible residues. These results indicate that the combined production of slag with co-gasification of municipal solid waste with the bottom ash constitutes an ideal approach to environmental conservation and resource recycling. 相似文献
7.
Volatilization behavior of lead from molten slag under conditions simulating municipal solid waste melting 总被引:1,自引:0,他引:1
Hiroyuki Nakada Naoto Mihara Yuuki Kawaguchi Shohichi Osada Dalibor Kuchar Hitoki Matsuda 《Journal of Material Cycles and Waste Management》2008,10(1):19-23
To reutilize molten slag derived from an ash melting process, the lead volatilization mechanism under reducing conditions
was investigated. Reducing conditions were established by introducing a CO-CO2-N2 gas mixture to the reactor or by adding graphite to the molten slag prior to the experiments. As samples, two types of simulated
molten slag composed of CaO-SiO2-Al2O3 mixed with PbO were used and the lead volatilization behavior was studied at 1773 K. It was found that the lead volatilization
rate increased on increasing the amount of reducing agent for both graphite and the CO-CO2 gas mixture. For the CO-CO2 reducing gas mixture, this increase was mainly attributed to PbO conversion to Pb. For the addition of graphite, the increase
in lead volatilization ratio was considered to partially result from PbO conversion to Pb and partially from a reaction of
graphite with SiO2 yielding volatile SiO. The volatile SiO gas was then emitted from the furnace, which brought about a reduction in the SiO2 content of the slag. As a result, the slag viscosity decreased, which led to an enhancement of the lead volatilization ratio. 相似文献
8.
Shohichi Osada Dalibor Kuchar Hitoki Matsuda 《Journal of Material Cycles and Waste Management》2009,11(4):367-375
In the present work, a shaft-type furnace model in which the furnace column is divided into multiple cells was proposed and
equilibrium reaction calculation software was used to describe the model. The model was used to study the effects of gasification
and melting conditions such as temperature, oxygen partial pressure, and chlorine content on the volatilization behaviors
of the low-boiling-point metals Na, K, Pb, and Zn during the gasification and melting process of municipal solid waste in
a shaft-type furnace. Consequently, the volatilization ratios of Na, K, Pb, and Zn compounds in the exhaust gas from a pilot
plant shaft-type furnace were found to be in good agreement with the calculation results, and the Na, K, Pb, and Zn compounds
were volatilized mainly as metal chlorides in the temperature range up to approximately 1173 K. With a further rise in temperature,
these low-boiling point metals were volatilized as metallic forms. It was found that almost 100% of Pb and Zn compounds were
volatilized regardless of the chlorine content in municipal solid waste; in contrast, the volatilization rates of Na and K
increased when the chlorine content increased. Finally, Na, K, Pb, and Zn compounds were converted from reduced metals to
metal chlorides such as NaCl, KCl, PbCl2, and ZnCl2 with an increase in the ratio of chlorine to each metal. 相似文献
9.
Morihiro Osada Nobuhiro Tanigaki Shin Takahashi Shin-ichi Sakai 《Journal of Material Cycles and Waste Management》2008,10(2):93-101
The End-of-life Vehicles Recycling Act went into effect on January 1, 2005, in Japan and requires the proper treatment of
airbags, chlorofluorocarbons (CFCs), and automobile shredder residue (ASR). The need for optimal treatment and recycling of
ASR, in particular, has been increasing year after year because ASR is regarded as being difficult to treat. Dioxin-related
compounds, brominated flame retardants (BFRs), heavy metals, chlorine and organotin compounds are all present in high concentrations
in ASR. The authors conducted ASR melting treatment tests using a 10-tons/day-scale direct melting system (DMS), which employs
shaft-type gasification and melting technology. The results obtained showed that dioxin-related compounds and BFRs were decomposed
by this melting treatment. The high-temperature reducing atmosphere in the melting furnace moved volatile heavy metals such
as lead and zinc into the fly ash where they were distributed at a rate of more than 90% of the input amount. This treatment
was also found to be effective in the decomposition of organotin, with a rate of decomposition higher than 99.996% of the
input amount. Via the recovery of heavy metals concentrated in the fly ash, all the products discharged from this treatment
system were utilized effectively for the complete realization of an ASR recycling system that requires no final disposal sites. 相似文献
10.
A. Matsuki Y. Iwasaka G.-Y. Shi H.-B. Chen K. Osada D. Zhang M. Kido Y. Inomata Y.-S. Kim D. Trochkine C. Nishita M. Yamada T. Nagatani M. Nagatani H. Nakata 《Water, Air, & Soil Pollution: Focus》2005,5(3-6):101-132
This study focuses on providing a direct insight into the process by which sulfate is formed on mineral dust surface in the
actual atmosphere. Six sets of aerosol measurements were conducted in the outskirts of Beijing, China, in 2002–2003 using
a tethered balloon. The mineralogy of individual dust particles, as well as its influence on the S (sulfur) loadings was investigated
by SEM-EDX analysis of the directly collected particles.
The mixed layer in the urban atmosphere was found to be quite low (500–600m), often appearing as a particle dense stagnant
layer above the surface. It is suggested that mineral dust is a common and important fraction of the coarse particles in Beijing
(35–68%), and that it is relatively enriched with Calcite (>28%).
An exceptional amount of S was detected in the mineral particles, which can be explained neither by their original composition,
nor by coagulation processes between the submicron sulfates and the dust. Heterogeneous uptake of gaseous SO2, and its subsequent oxidation on dust was suggested as the main pathway that has actually taken place in the ambient environment.
The mineral class found with the largest number of particles containing S was Calcite, followed by Dolomite, Clay, Amphibole
etc., Feldspar, and Quartz. Among them, Calcite and Dolomite showed distinctly higher efficiency in collecting sulfate than
the other types.
A positive correlation was found with the number of S containing particles and the relative humidity. Calcite in particular,
since almost all of its particles was found to contain S above 60% r.h. On the other hand, the active uptake of SO2 by the carbonates was not suggested in the free troposphere downwind, and all the mineral classes exhibited similar S content.
Relative humidity in the free troposphere was suggested as the key factor controlling the SO2 uptake among the mineral types. In terms of sulfate loadings, the relationship was not linear, but rather increased exponentially
as a function of relative humidity. The humidity-dependent uptake capacity of mineral types altogether showed an intermediate
value of 0.07 gSO4
2− g−1 mineral at 30% r.h. and 0.40 gSO4
2− g−1 mineral at 80%, which is fairly consistent with laboratory experiments. 相似文献